For example, a provider providing a service to users (hereinafter also referred to simply as a provider) sometimes acquires and analyzes a communication packet flowing in a network (hereinafter also referred to simply as a packet), and monitors operation state of a system in operation and a network.
Specifically, the provider installs a network distribution device (for example, a network tap) on a network. Then, the network distribution device acquires packets flowing in the network and performs mirroring of the acquired packets. Thereafter, the network distribution device transmits packets generated by mirroring to a packet capture apparatus (hereinafter also referred to simply as a capture apparatus) which then performs packet analysis. The capture apparatus is thus allowed to accumulate mirror packets of the analysis target into a storage device. Hereinafter, a packet to be mirrored in the network distribution device (packet which the network distribution device acquires from the network) is also referred to as a system packet, and a packet generated by mirroring of the system packet (packet which the capture apparatus analyzes) is also referred to as a mirror packet. Related techniques are disclosed in Japanese Laid-open Patent Publication Nos. 9-128260 and 2012-094998.